Instruments for direct d31, d32 and d33 measurement

The patented ESPY31 provides SI‑traceable measurement of the in‑plane direct piezoelectric charge coefficients d₃₁ and d₃₂. Measurement uncertainty is quantified through a traceable calibration chain for both force and charge channels.

The integrated force cell is calibrated against NIST mass standards and the local value of g. Electric charge calibration is performed with a traceable current or voltage source. Both calibrations are carried out in‑house, eliminating the need for potentially unstable piezoelectric reference samples.

The system achieves 100 fA current resolution with sub‑picocoulomb charge accuracy. This measurement range allows reliable determination of direct d₃₁ and d₃₂. in materials with weak piezoelectric response.

Patented clamps and flexure guidance minimize clamping artifacts, suppress off-axis strain, and enforce a strictly tensile geometry. This yields uniform on-axis strain with zero off-axis contribution, by suppressing parasitic contributions from other components of the piezoelectric tensor. Such components can be d₃₃ (out-of-plane compression or bending), shear components d₁₅, d₂₄ (transverse motion or twisting), flexional (bending) artifacts (a non-uniform stress gradient through the sample’s thickness). The clamp design prevents slippage and reduces measurement uncertainty.

Determination of the direct piezoelectric charge coefficients is based on directly measured quantities—generated charge Q, applied force F, and the defined electrode area. This avoids reliance on bending‑beam curvature interpretations or assumptions concerning strain gradients.

The system measures capacitance, dielectric loss, and leakage current, under both zero‑bias and DC‑bias conditions. Measurements may be taken before, during, and after mechanical excitation, enabling assessment of dielectric response, electromechanical fatigue, and electrode degradation during cyclic loading.

Frequency‑dependent response is obtained using automated sweeps. This includes resonance mapping in addition to static coefficient determination.

When operated in a controlled climate chamber, measurements can be performed as a function of temperature and humidity. This allows investigation of phase transitions, thermal cycling, and environmental ageing mechanisms. Susceptibility to humidity and reactive atmospheres can also be probed. In this way, intrinsic material behavior is linked directly to operational reliability under realistic service conditions.

The instrument is designed for free‑standing film specimens. The standard sample dimension is 2 mm×4.5 mm, with electrodes applied to both major surfaces.

* For more specifications and details, contact us at sales@aixacct.com

The ESPY33 implements a refined Berlincourt method for direct determination of the piezoelectric charge coefficient d₃₃. Its core element is a patented integrated force measurement cell, which is mechanically aligned with the sample fixture to apply axial loads without lateral components.

Conventional measurement devices for direct piezoelectric coefficient assessment often rely on reference piezoelectric materials, which can drift or degrade over time due to stress, temperature, or humidity, compromising accuracy and reliability. In contrast, the ESPY33 is traceably calibrated and does not rely on reference sample measurement.

The applied force is traceably calibrated against NIST mass standards, and the local gravitational acceleration g. Electric charge is calibrated using a traceable current or voltage source. Both channels are calibrated in-house, providing full SI traceability without reliance on reference piezoelectric standards that degrade with stress, temperature, or humidity.

The system achieves 100 fA current resolution with sub‑picocoulomb charge accuracy. This sensitivity supports characterization of materials with weak piezoelectric response, where generated signals are close to typical noise levels.

Compliant piezoelectric materials tend to be susceptible to deformation, which can lead to inaccurate measurements of the piezoelectric coefficients of these materials. Electrode geometry has been optimized for uniform electric field distribution and homogeneous mechanical stress. Preload force (static force) can be adjusted by the user, minimizing depoling effects and improving measurement repeatability for compliant materials.

Determination of d₃₃ is derived directly from measured charge Q, applied force F, and known electrode area.

In parallel with piezoelectric measurements, the instrument can record capacitance, dielectric loss (tan δ), and leakage current. Data acquisition may be performed before, during, or after mechanical excitation, with optional DC bias applied. This supports analysis of dielectric behavior, electromechanical fatigue, and electrode stability under combined electrical and mechanical stress.

Frequency‑swept operation enables assessment of both mechanical and electrical resonances, extending characterization beyond quasi‑static coefficient values.

ESPY33 can be operated within a temperature–humidity chamber. This enables studies of temperature‑dependent coefficients, ferroelectric phase transitions, thermal cycling behaviour, ageing, and humidity or atmosphere induced degradation. Correlation of intrinsic d₃₃ response with environmental conditions enables assessment of long-term reliability under realistic service environments.

Electroded samples provide well‑defined measurement volume and are recommended. Non‑electroded specimens may also be measured; in this case the effective interaction volume is determined by electrode–sample contact area.

The ESPY33 is ideal for manufacturers, researchers, and institutions requiring accurate evaluation of piezoelectric materials’ functional properties. Applications span various industries, including medical imaging, energy harvesting, and flexible actuators.

* For more specifications and details, contact us at sales@aixacct.com

Handcrafted in Germany and designed by Electrosciences Ltd (UK), the ESPY33 ensures high precision, excellent measurement repeatability, and long-lasting performance.